For small penis caused by low testosterone level, applying testosterone before adulthood can improve the condition, promote the enlargement and thickening of the penis, and gradually restore the normal level. For short penis caused by other factors, the application of testosterone is not effective. The causes of penile shortening are more complex, such as low testosterone levels, which can lead to a small penis. Adolescent males with this condition, after following the doctor’s instructions to apply testosterone undecanoate, methyltestosterone tablets and other drugs, can promote the thickening and growth of the penis, to improve the symptoms of penile shortening. In addition to this, short penis may also be related to genetic factors, penile trauma, circumcision and other factors. Applying testosterone or taking other medications cannot improve the condition. Penis shortening caused by such factors can be treated with penile lengthening surgery in a timely manner. Different patients have different causes of penile shortening, so they should go to a specialized male hospital for examination and diagnosis, and then follow the doctor’s instructions for treatment.